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Marathoning Is Hard; So Is Science Journalism

Nov 9, 2010

By Greg CrowtherLast month the scientific journal PLoS Computational Biology published an article by Benjamin I. Rapoport titled Metabolic Factors Limiting Performance in Marathon Runners. On the whole, I found the article unsatisfying. What really drove me nuts, though, was the quantity and quality of the media coverage devoted to this article.The first story I happened to see was Marathoning Made Easy by Laura Sanders of Science News. According to Sanders, "Benjamin Rapoport’s mathematical formula . . . shows the speediest pace any marathoner can sustain for the entire race."I beg to differ. Rapoport attempts to define the range of paces that various people can sustain without running out of glycogen, a form of carbohydrate stored in the muscles and liver. But a marathoner’s top pace depends on other things too -- training, for example.Speaking of glycogen, the word "glycogen" isn't actually used in the story. I understand that when the entire article is less than 500 words, there isn't a lot of room to introduce and define technical terms. But since the topic of Rapoport's study is the circumstances under which stored carbohydrates are and are not sufficient, shouldn't some mention be made of how and where they are stored?The Science News story does attempt to define VO2 max, which is one of the key factors included in Rapoport's calculations. We are told that "VO2 max indicates how efficiently a body consumes oxygen," which I find more misleading than helpful. VO2 max is the maximum rate at which the body can use oxygen, but its efficiency in using that oxygen to do work is a separate issue -- one encapsulated by the term running economy.

Example:
For an averagely fit, 11 stone runner aged 35
The Marathon Formula calculates that to run 4 hours 35 mins he needs to eat 1,546 calories of carbohydrate (eight servings of pasta or 10 of rice) 36 hours to 12 hours before the race. (This is on top of normal meals)
To run 3 hours 10 mins need to eat 2,900 calories (15 servings of pasta or 20 of rice)

One gets the impression that carbo-loading can turn slugs into racehorses. To go from a 4:35 to a 3:10, all you apparently need to do is eat more! (Heck, why not shovel in even MORE carbs and go for a 2:30?)My informal survey of media coverage of the Rapoport article also included online stories found at Competitor.com, Economist.com, LiveScience.com, NPR.org, Reuters.com, andRunnersWorld.com. I checked them for various attributes, as listed in the table, below. In certain respects I was pleasantly surprised; most stories mentioned the journal in which Rapoport's study was published (thus making it easier for interested readers to find), and several included links to the study itself and/or the online calculator based upon it.Explanations of major points, however, were often disappointing. For instance, all of the stories note that VO2 max is an important part of the calculations, but that raises the question of how the online calculator works, since it doesn’t take VO2 max as an input. Of the six stories that link to the online calculator, only one clearly explains how VO2 max is estimated from heart rate data. Two others simply note that such an estimate can be made, and the last three don’t mention the issue at all.Increasing one’s pace increases the risk of hitting the wall, and this is a central theme of Rapoport’s article and the media coverage of it. But why exactly is this true? It isn’t sufficient to say that carbohydrate use increases at higher speeds; the race doesn’t last as long at higher speeds either, so if carbohydrate use per unit time were linearly proportional to running speed, there would be no problem. The wrinkle is that carbohydrate use actually increases more dramatically than that because of the interplay between carbohydrate use and fat use. Only three of the eight stories refer to this fact.What’s lacking here is a thorough understanding of the research that can be used to explain it (How exactly does the formula work?) and place it in the context of its field (How does this go beyond previous studies? What is still unknown?) and readers' own lives (What is the practical payoff?). Of course, these stories do offer a "take-home message" to readers – here's a calculator to tell you how many extra carbs to eat before a marathon! -- but that message is generally delivered without any critical appraisal of the calculator's usefulness.I’m not sure how much of the blame for this belongs to the journalists themselves. As science writers, they may have to churn out stories on everything from subatomic particles to ecological disasters, and they don’t have time to become experts on everything they write about. Nonetheless, there’s something wrong with a system that consistently gives us mediocre summaries of science research.I certainly don’t have all the answers, but I think it would be great if science writers could focus on a smaller number of topics and explore them more deeply. After all, preparing a really good story is difficult and time-consuming -- just like preparing for a really good marathon.[Click table, below, to enlarge.]

Greg Crowther, a microbiologist at the University of Washington in Seattle, is one of the best ultramarathoners in the United States. He was the 2007 U.S. champion at 50 and 100-K and won the 2009 JFK 50 Miler in 5:50:13. His blog is My Track Record.Other Voices welcomes submissions. To submit your post for consideration, e-mail us at rwwebedit@rodale.com. Please write "Other Voices" in the subject line. Runner's Word reserves the right to edit posts for length and clarity. We will contact you if your post is being considered for publication.

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